Upon entry of spacecraft into the atmosphere of the earth or other planets or planetary moons, heat shields and/or deceleration structures are needed for decelerating the spacecraft and protecting it from excessive heat due to the arising frictional heating as the spacecraft passes through the atmosphere. New spacecraft planned for future space missions are relatively large and heavy in comparison to present spacecraft, so that such future spacecraft will not always be sufficiently protected by the current conventional heat shield arrangements that are mounted directly on the surface of the spacecraft. For example, such conventional arrangements involve heat-resistant ceramic tiles, heat ablatable materials and/or heat insulation materials mounted on the surface of the spacecraft. Also, relatively large heat resistant braking shields, parachutes or umbrellas and/or heat shields that protrude outwardly beyond the dimensions of the spacecraft itself will be needed. However, due to the substantial size of such arrangements, it is difficult or impossible to accommodate such arrangements in a launch rocket or in a cargo bay of the spacecraft during the launch and space mission thereof before atmospheric entry when the arrangement must be deployed.
In view of the above, inflatable flexible structures of various configurations have become known as heat shield and deceleration structures, for example as disclosed in U.S. Pat. No. 4,832,288 (Kendall et al.). To achieve the required heat resistance to withstand the high heat loads arising upon entry into the atmosphere, such inflatable flexible structures either must be provided with an ablative heat protection arrangement, or must be inflated to form a very large balloon structure of heat resistant material. These known systems, however, often suffer the disadvantage of a very high volume in the stowed condition before deployment, a very high energy demand for deployment, and a high mass especially due to the necessary compressed gas tanks containing the compressed gas needed for inflation.
To address the above disadvantages, the German Patent Publication DE 691 01 021 T2 (translation of EP 0 453 361) discloses an apparatus for thermal protection and deceleration of a spacecraft upon entry into the atmosphere, including an unfoldable deployable shield in the form of a foldable structure of high temperature resistant panels that are deployably mounted on the outside structure of the spacecraft. This arrangement requires relatively little space compared to other conventional arrangements. The panels have various different shapes and are articulately connected with one another, and are unfoldable or deployable to form a contiguous or interconnected umbrella, parachute or shield by operation of a common actuating apparatus. This arrangement is relatively complex in structure and operation.
Furthermore, in the field of satellite construction, various different foldable structures for large antennas in terrestrial and orbital applications are known. These foldable antenna structures, however, consist of conventional fiber reinforced composite materials and are only suitable for small temperature fluctuations of about ±50° C. and for relatively low mechanical loading. Namely, such foldable antenna structures are not suitable for heat shields and deceleration structures for spacecraft entering the atmosphere.